Aftertreatment device

ABSTRACT

An aftertreatment device ( 10, 110, 210 ) for use on an engine ( 16 ) having a cylinder head ( 14 ) includes an exhaust manifold ( 12, 112, 212 ) having an outlet ( 26 ), and a plurality of catalyst assemblies ( 28 ) located upstream of the outlet. The catalyst assemblies ( 28 ) define an exhaust gas passageway ( 38, 138, 238 ) that is in fluid communication with the engine ( 16 ) and in fluid communication with the outlet ( 26 ). A catalyst substrate ( 30 ) is disposed in the catalyst assemblies ( 28 ).

FIELD OF THE INVENTION

The present invention relates generally to aftertreatment systems in vehicles. More specifically, the present invention relates to an aftertreatment system having improved efficiency.

BACKGROUND OF THE INVENTION

Currently, the aftertreatment system of a vehicle includes large catalyst assemblies mounted on the downstream side of the engine in the chassis of the vehicle. The catalyst assemblies contain catalyst substrates to chemically react with the undesirable emissions components in the exhaust gas. This configuration of aftertreatment device creates several problems. One problem is that the catalyst assemblies are large, making them difficult to package in the chassis of the vehicle downstream of the engine. Additionally, by the time the exhaust gases reach the catalyst assemblies, the gases have cooled. This is problematic because the catalysts function more efficiently at higher temperatures. Further, the catalyst substrates located inside the catalyst assemblies create a back-pressure and a restriction in the engine's exhaust system that can cause the engine performance to degrade.

The above-identified problems relating to the large size of the assemblies have previously been addressed by making the catalyst assemblies smaller than required for optimum performance. However, decreasing the size of the catalyst assemblies has the tendency to increase the restriction on the engine. Other prior art aftertreatment systems incorporate a double-walled exhaust pipe or heat shields to retain the heat in the exhaust gases to improve the efficiency of the catalysts. However, incorporating double-walled pipes and heat shields requires more materials and a more complicated design.

SUMMARY OF THE INVENTION

An aftertreatment device for use on an engine having a cylinder head includes an exhaust manifold having an outlet, and at least one catalyst assembly located upstream of the outlet. The at least one catalyst assembly defines an exhaust gas passageway that is in fluid communication with the engine and in fluid communication with the outlet. A catalyst substrate is disposed in the catalyst assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view of an aftertreatment device mounted in an exhaust manifold in accordance with the invention.

FIG. 2 is a section view of the aftertreatment device taken along line A-A of FIG. 1 in accordance with the invention.

FIG. 3 is a schematic front view of an alternate aftertreatment device mounted between the exhaust manifold and a cylinder head in accordance with the invention.

FIG. 4 is a section view of the aftertreatment device taken along line B-B of FIG. 3 in accordance with the invention.

FIG. 5 is a schematic front view of a second alternate aftertreatment device mounted in the cylinder head in accordance with the invention.

FIG. 6 is a section view of the aftertreatment device taken along line C-C of FIG. 5 in accordance with the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to FIG. 1 and FIG. 2, an aftertreatment device is indicated generally at 10, and includes an exhaust manifold 12. As is known in the art, the exhaust manifold 12 is attached to and extends from a cylinder head 14 of an engine 16, and is designed to collect the exhaust gas from the cylinder head and funnel it into an exhaust pipe (not shown). The cylinder head 14 includes a plurality of exhaust channels 18 for discharging exhaust from the engine 16 in the direction of flow “F”. In the engine 16, there are four exhaust channels 18 on each side of a “V”-shaped cylinder block for a total of eight exhaust channels (only one-side of the “V”-shape being depicted in FIG. 1 through FIG. 6).

The exhaust manifold 12 includes a neck 20 extending from each exhaust channel 18 on the cylinder head 14, and a body 22 in fluid communication with each neck. The neck 20 is attached to the cylinder head 14, and has a generally increasing width in the direction of flow “F”. Downstream of the neck 20 (in the direction of flow “F”), a cylindrical portion 24 is attached to each wide-end of the neck. The body 22 is attached to or integrally formed with each cylindrical portion 24 downstream of the cylindrical portion. In the exhaust manifold 12, the four cylindrical portions 24 are integrally formed with the body 22.

At the downstream end of the body 22 is an exhaust manifold outlet 26. In this configuration, the exhaust gas flows from the exhaust channel 18 in the cylinder head 14, into the neck 20, through the cylindrical portion 24, through the body 22, and out the outlet 26 of the exhaust manifold 12.

A generally cylindrical catalyst assembly 28 is mounted inside each cylindrical portion 24 of the exhaust manifold 12 such that the catalyst substrate 30 is generally centered in the cylindrical portion. Advantageously, the catalyst assembly 28 includes a honeycomb catalyst substrate 30 having an intumescent or a non-intumescent mat 32 disposed around the generally circular, peripheral surface of the catalyst substrate, however other configurations are contemplated. For example, the catalyst assembly 28 may include other layers, such as insulation or a housing, as is known in the art. Additionally, the honeycomb catalyst can be ceramic, metal, or made of any other material.

The cylindrical portion 24 of the exhaust manifold 12 circumscribes the catalyst assembly 28, and the mat 32 engages an inner surface of the cylindrical portion along the length of the catalyst substrate. An inlet surface 34 and an outlet surface 36 of the catalyst assembly 28 advantageously are not engaged by the mat 32, but instead are exposed to the exhaust flow “F” from the exhaust channel 18. The longitudinal axis defined by the cylindrical portion 24 is angled approximately 30-degrees with respect to the exhaust channel 18, however angles from 0 to 360-degrees are contemplated.

The catalyst assemblies 28 are disposed in parallel with respect to each other, and the body 22 is disposed in fluid communication with each catalyst assembly 28 to form an exhaust passageway 38. The exhaust gas flow path “F” goes through the catalyst assemblies 28 in the exhaust passageway 38. At least one catalyst assembly 28 can be on the exhaust passageway 38, located upstream of the outlet 26.

The body 22 extends generally transverse to the direction of the flow “F” through each of the cylindrical portions 24. Downstream, the flow “F” in the body 22 is generally parallel with an opposing surface 40 of the body. Adjacent the outlet 26 of the exhaust manifold 12, the opposing surface 40 is contoured to direct the exhaust gases “F” out of the manifold through the outlet, which is generally angled 90-degrees with respect to the opposing surface 40.

For optimal performance, the aftertreatment device 10 requires a minimum internal volume to accommodate the catalyst substrate and the exhaust gas. An exemplary aftertreatment device for a V8 engine could have the following specifications:

Diameter of Can Length of Can Quantity of Catalyst Total Volume (inches) (inches) assemblies (square inches) 3 3 8 170 3 3.7 8 209 4 4.3 8 432

By locating at least one catalyst assembly 28 in the exhaust manifold 12, the temperature of the exhaust gases reaching the catalysts is increased, improving their efficiency. Further, the increased efficiency of the catalysts could lead to the use of substrates having a lower cell density, which would result in less restriction on the engine.

Referring now to FIG. 3 and FIG. 4, an alternate aftertreatment device is indicated generally at 110, and includes a catalyst manifold 100 located upstream of an exhaust manifold 112 and downstream of a cylinder head 14. The cylinder head 14 includes a plurality of exhaust channels 18 for discharging exhaust from the engine 16 in the direction of flow “F”.

The catalyst manifold 100 includes a first neck 120 extending from each exhaust channel 18 on the cylinder head 14, a cylindrical portion 124 attached to each wide-end of the neck, and a second neck 102 extending from the downstream end of the cylindrical portion. Each first neck 120 is attached to or integrally formed with each cylindrical portion 124. In the catalyst manifold 100, the four cylindrical portions 124 are attached to or integrally formed with each other.

At the downstream end of the second neck 102, which decreases in width in the direction of flow “F”, is an exhaust manifold 112 having a body 122 and an outlet 26. In this configuration, the exhaust gas flows from the exhaust channel 18 in the cylinder head 14, into the first neck 120, through the cylindrical portion 124, through the second neck 102, through the body 122, and out the outlet 26 of the exhaust manifold 112.

A generally cylindrical catalyst assembly 28 is mounted inside each cylindrical portion 124 of the catalyst manifold 100 such that the catalyst substrate 30 is generally centered in the cylindrical portion 124. A mat 32 is disposed around the peripheral surface of the catalyst substrate 30, however other configurations are contemplated. The catalyst assemblies 28 are disposed in parallel with respect to each other, and the body 122 is disposed in fluid communication with each catalyst assembly 28 to form an exhaust passageway 138. It is contemplated that one catalyst assembly 28 can form the exhaust passageway 138.

The cylindrical portion 124 of the catalyst manifold 100 circumscribes the catalyst assembly 28, and the mat 32 engages an inner surface of the cylindrical portion along the length of the catalyst substrate 30. The longitudinal axis defined by the cylindrical portion 124 is generally aligned with the exhaust channel 18, however angled orientations are contemplated.

By locating the catalyst assemblies 28 in a catalyst manifold 100 between the cylinder head 14 and the exhaust manifold 112, the temperature of the exhaust gases reaching the catalysts is increased. The increased temperature improves the efficiency of the catalyst assemblies 28.

Referring now to FIG. 5 and FIG. 6, a second alternate aftertreatment device is indicated generally at 210, and is located in the cylinder head 214. The cylinder head 214 includes a plurality of exhaust channels 18 for discharging exhaust from the engine 16 in the direction of flow “F”.

The cylinder head 214 includes a neck 220 in fluid communication with the exhaust channel 18, and a cylindrical portion 224 downstream of the wide-end of the neck. At the downstream end of the cylindrical portion 224 is an exhaust manifold 212 having a body 222 and an outlet 26. In this configuration, the exhaust gas flows from the exhaust channel 18, through the neck 220, through the cylindrical portion 224, through the body 222, and out the outlet 26 of the exhaust manifold 212.

A generally cylindrical catalyst assembly 28 is mounted inside each cylindrical portion 224. A mat 32 is disposed around the peripheral surface of the catalyst substrate 30. The catalyst assemblies 28 are disposed in parallel with respect to each other, and the body 222 is disposed in fluid communication with each catalyst assembly to form an exhaust passageway 238. It is contemplated that the catalyst assembly 28 can be inserted in a recess in the cylinder head 214, or integrally formed with the cylinder head.

By locating the catalyst assemblies 28 in the cylinder head 214, the temperature of the exhaust gases reaching the catalysts is increased. The increased temperature improves the efficiency of the catalyst assemblies 28.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. 

1. An aftertreatment device for use with an engine having a cylinder head, comprising: an exhaust manifold attached to the engine and having an outlet; at least one catalyst assembly located upstream of an exhaust manifold outlet, the at least one catalyst assembly defining an exhaust gas passageway that is in fluid communication with the engine and in fluid communication with the outlet; and a catalyst substrate disposed in the at least one catalyst assembly.
 2. The aftertreatment device of claim 1 wherein the at least one catalyst assembly comprises eight catalyst assemblies on the engine.
 3. The aftertreatment device of claim 1 wherein the at least one catalyst assembly is located in the cylinder head.
 4. The aftertreatment device of claim 1 wherein the at least one catalyst assembly is located between the cylinder head and the exhaust manifold.
 5. The aftertreatment device of claim 1 wherein the at least one catalyst assembly is located in the exhaust manifold.
 6. An aftertreatment device for use on an engine having a cylinder head, comprising: an exhaust manifold attached to the engine and having an outlet; a plurality of catalyst assemblies located in the exhaust manifold and defining an exhaust gas passageway that is in fluid communication with the engine and in fluid communication with the outlet; and a catalyst substrate disposed in the plurality of catalyst assemblies.
 7. The aftertreatment device of claim 6 wherein the plurality of catalyst assemblies comprises eight catalyst assemblies for the engine.
 8. The aftertreatment device of claim 6 wherein the exhaust manifold further comprises at least one neck extending the cylinder head, the neck having a generally increasing width in the direction of flow towards the outlet.
 9. The aftertreatment device of claim 8 wherein the exhaust manifold further comprises a body in fluid communication with the at least one neck.
 10. The aftertreatment device of claim 9 wherein the outlet is disposed on the body of the exhaust manifold.
 11. The aftertreatment device of claim 6 wherein the catalyst assembly comprises a honeycomb catalyst substrate having a mat disposed around the generally circular, peripheral surface of the catalyst substrate.
 12. An aftertreatment device for use with an engine having a cylinder head, comprising: an exhaust manifold attached to the engine and having an outlet; a plurality of catalyst assemblies located between the cylinder head and the exhaust manifold, the catalyst assemblies defining an exhaust gas passageway that is in fluid communication with the engine and in fluid communication with the outlet; and a catalyst substrate disposed in the plurality of catalyst assemblies.
 13. The aftertreatment device of claim 12 wherein the plurality of catalyst assemblies comprises eight catalyst assemblies for the engine.
 14. The aftertreatment device of claim 12 further comprises a catalyst manifold disposed between the cylinder head and the exhaust manifold.
 15. The aftertreatment device of claim 14 wherein the catalyst manifold comprises a first neck extending from the cylinder head, a cylindrical portion attached to the neck, and a second neck extending from the cylindrical portion, wherein the first neck increases in width and the second neck decreases in width in the direction of flow towards the outlet.
 16. The aftertreatment device of claim 15 wherein the catalyst assembly is disposed in the cylindrical portion of the catalyst manifold.
 17. An aftertreatment device for use with an engine having a cylinder head, comprising: an exhaust manifold attached to the engine and having an outlet; a plurality of catalyst assemblies located in the cylinder head, the catalyst assemblies defining an exhaust gas passageway that is in fluid communication with the engine and in fluid communication with the outlet; and a catalyst substrate disposed in the plurality of catalyst assemblies.
 18. The aftertreatment device of claim 17 wherein the plurality of catalyst assemblies comprises eight catalyst assemblies for the engine.
 19. The aftertreatment device of claim 17 wherein the catalyst assemblies are disposed in a recess of the cylinder head.
 20. The aftertreatment device of claim 17 wherein the catalyst assemblies are integrally formed with the cylinder head. 